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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 9 |
| 3 | 23 |
| 4 | 49 |
| 5 | 175 |
| 6 | 321 |
| 7 | 1189 |
| 8 | 3025 |
| 9 | 12111 |
| 10 | 28492 |
| 11 | 113409 |
| 12 | 251513 |
| 13 | 1068440 |
| 14 | 2629980 |
| 15 | 11690210 |
| 16 | 28498852 |
| 17 | 128871588 |
| 18 | 298890814 |
| 19 | 1309837146 |
[4,9,23,49,175,321,1189,3025,12111,28492,113409, 251513,1068440,2629980,11690210,28498852, 128871588,298890814,1309837146] |